Application of an immobilized microbial consortium for the treatment of pharmaceutical wastewater: Batch-wise and continuous studies

In the present investigation, a microbial consortium consisting of four bacterial strains was selected for the treatment of pharmaceutical industry wastewater. The consortium was immobilized on a natural support matrix-Luffa and used for the treatment of real-time pharmaceutical wastewater in batch and continuous processes. The batch process was carried out to optimize the culture conditions and monitor the enzymatic activity. An array of enzymes such as alcohol dehydrogenase, aldehyde dehydrogenase, monooxygenase, catechol 2,3-dioxygenase and hydroquinol 1,2-dioxygenase were produced by the consortium. The kinetics of the degradation in the batch process was analyzed and it was noted to be a first-order reaction. For the continuous study, an aerobic fixed-film bioreactor (AFFBR) was utilized for a period of 61 days with variable hydraulic retention time (HRT) and organic loading rate (OLR). The immobilized microbes treated the wastewater by reducing the COD, phenolic contaminants and suspended solids. The OLR ranged between (0.56 ± 0.05) kg COD·m^-3 d^-1 to 3.35 kg COD·m^-3·d^-1 and the system achieved an average reduction of 96.8% of COD, 92.6% of phenolic compounds and 95.2% of suspended solids. Kinetics of the continuous process was interpreted by three different models, where the modified Stover Kincannon model and the Grau second-order model proved to be best fit for the degradation reaction with the constant for saturation value, KL being 95.12 g·L^-1·d^-1, the constant for maximum utilization of the substrate U_max being 90.01 g·L^-1 d^-1 and substrate removal constant K_Y was 1.074 d^-1 for both the models. GC-MS analysis confirmed that most of the organic contaminants were degraded into innocuous metabolites.     

用CuO/A12O3/堇青石催化剂选择性催化还原脱硝的实验和动力学研究

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy of 94.01 kJ•mol1 and the corresponding pre-exponential factor of 3.39×108 cm3•g1•s1 when NH3 is excessive. However, when NH3 is not enough, an Eley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ•mol1, the corresponding A of 2.94×109 cm3•g1•s1, heat of adsorption ΔHads of 87.90 kJ•mol1 and the corresponding Aads of 9.24 cm3•mol1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reactor design and engineering scale-up.     

Helium extraction from natural gas using DD3R zeolite membranes

Helium (He) is commercially produced from natural gas by low-temperature condensation. The process is energy extensive because of the extremely low He concentration (<0.3%) and the operation at cryogenic temperature. Herein we demonstrated DD3R zeolite membrane was efficient to extract He from natural gas at atmosphere temperature. The membrane performance was evaluated in terms of temperature, pressure and molar fractions. The overall membrane performance was dominated by the diffusivity selectivity. The single He permeance and ideal He/CH₄ selectivity were 5.8×10^-9 mol·m^-2·s^-1·Pa^-1 and 79 under a feed pressure of 1.3 MPa. Even though He concentration was as low as 0.22%, the He permeance and He/CH₄ mixture selectivity were 3.0×10^-9 mol·m^-2·s^-1·Pa^-1 and 44 at 0.7 MPa. During the long-term operation (～130 h) the membrane performance was stable even the feed mixture containing 3.6% ethane as contaminations. The results approved the feasibility of DD3R zeolite membranes for He extraction from natural gas.     

铁矿石烧结中混合料特性对火焰烽面与烧结性能的影响机理研究

通过中试规模烧结杯试验和综合烧结模型，将返矿平衡和非平衡条件相结合，研究了混合料特性（烧结碱度、焦炭和水分添加量）对火焰烽面特性和烧结性能的影响机理。模拟研究涉及多种烧结条件下的125个烧结杯工况。为揭示火焰烽面区域中熔体生成与凝固行为，使用FactSage软件进行化学热力学模拟并建立了更完善的熔化和凝固子模型。模拟与试验研究表明，随着碱度和焦炭添加量的变化，火焰烽面速度、成品率、焦比和利用系数会出现局部最大或最小值。在本文烧结条件下，最大利用系数工况为碱度2.0、水分7.7%、焦炭6.4%。最小焦比工况为碱度2.0、水分6.5%、焦炭6.4%。最小焦比和最大利用系数的条件并不相同，而最终烧结操作取决于每个烧结厂的控制目标。     

Regulatable pervaporation performance of Zn-MOFs/polydimethylsiloxane mixed matrix pervaporation membranes

Pervaporation (PV) is an emerging separation technique for liquid mixture. Mixed matrix membranes (MMMs) often demonstrate trade-off relationship between separation factor and flux. In this study, by changing the organic linkers (2-methyl imidazolate, imidazole-2-carboxaldehyde, 2-ethyl imidazolate), ZIF-8, ZIF-90 and MAF-6 were prepared and filled in polydimethylsiloxane (PDMS) membranes for dealcoholization of 5% (mass) n-butanol solution, and the membranes properties and pervaporation performances were adjusted. Compared with the pure PDMS membrane, the addition of ZIF-8 resulted in a 9% increase in flux (1136 g·m^-2·h^-1) and a 22.5% increase in separation factor (28.3), displaying anti-trade-off effect. For the MAF-6/PDMS MMMs (2.0% mass loading), the pervaporation separation index (PSI) and separation factor were 32347 g·m^-2·h^-1 and 58.6 respectively (increased by 34% and 154% in contrast with that of the pure PDMS membrane), and the corresponding permeation flux was 552 g·m^-2·h^-1, presenting great potential in the removal butanol from water. It was deduced that the large aperture size combined with moderate hydrophobicity of metal-organic frameworks (MOFs) favor the concurrent increase in permeability and selectivity.     

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

In developing countries, high cost of conventional wastewater treatment is a major hindrance in its application. Constructed wetlands (CWs) offer low-cost and effective solution to this issue. The current study aimed to evaluate an innovative maneuver of CWs i.e. hybrid flow constructed wetlands (HCWs) for municipal wastewater (MWW). The HCWs included two lab scale CWs; one horizontal and one vertical, in series. Local plant species were used. HCWs were operated in both, batch and continuous mode. Batch mode was used to (1) optimize detention time and (2) find pollutants removal efficiency. Continuous operation (at batch optimized retention time) was carried out for the evaluation of mass removal rate, r (g·m^-2·d^-1), volumetric rate constant, K_v (per day) and areal rate constant, K_a (m·d^-1). Among two local plants tested, Pistia stratiotes gave better removal efficiency than Typha. Optimum detention time in HCWs was found to be 8 days (4 + 4 each). The optimum COD, BOD, TSS, TKN and P removal observed for Pistia stratiotes planted HCWs was 80%, 84%, 82%, 71% and 88% respectively. Effluent standards for COD, BOD and TSS were met at optimum conditions. The values of K_a and K_v demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.     

Immobilization of trophic anaerobic acetogen for semi-continuous syngas fermentation

The massive consumption of fossil energy forces people to find new sources of energy. Syngas fermentation has become a hot research field as its high potential in renewable energy production and sustainable development. In this study, trophic anaerobic acetogen Morella thermoacetica was successfully immobilized by calcium alginate embedding method. The ability of the immobilized cells on production of acetic acid through syngas fermentation was compared in both airlift and bubble column bioreactors. The bubble column bioreactor was selected as the better type of bioreactor. The production of acetic acid reached 32.3 g·L^-1 in bubble column bioreactor with a space-time yield of 2.13 g·L^-1·d^-1. The immobilized acetogen could be efficiently reused without significant lag period, even if exposed to air for a short time. A semi-continuous syngas fermentation was performed using immobilized cells, with an average space-time acetic acid yield of 3.20 g·L^-1·d^-1. After 30 days of fermentation, no significant decrease of the acetic acid production rate was observed.     

Hydrophobic modification of SAPO-34 membranes for improvement of stability under wet condition

SAPO-34 zeolite membranes show high efficiency for CO₂/CH₄ separation but suffer from the reduction of separation performance when exposed to humid atmosphere. In this work, n-dodecyltrimethoxysilane (DTMS) was used to modify the hollow fibers supported SAPO-34 membranes to increase the external surface hydrophobicity and thus sustain their performance under moisture environment. The modified membranes were fully characterized. Their separation performance was extensively investigated in both dry and wet gaseous systems and compared with the un-modified ones. The un-modified SAPO-34 membrane exhibited a high separation selectivity of 160 and CO₂ permeance of 1.18×10^-6 mol·m^-2·s^-1·Pa^-1 for separation of dry CO₂/CH₄ at 298 K. However, its separation selectivity declined to 0.9 and the CO₂ permeance was only about 1.7×10^-8 mol·m^-2·s^-1·Pa^-1 for wet CO₂/CH₄ at same temperature. High temperature (e.g. 353 K) could reduce the effect of moisture to improve SAPO-34 separation selectivity, but further increasing temperature (e.g. 373 K) led to decrease in CO₂/CH₄ separation selectivity. A significant decrease of selectivity was observed at higher pressure drop. The modified SAPO-34 membrane showed decreased CO₂ permeance but increased separation selectivity for dry CO₂/CH₄ gas mixture, and super performance for wet CO₂/CH₄ gas mixture due to the improved hydrophobicity of membrane surface. A separation selectivity of 65 and CO₂ permeance of 4.73×10^-8 mol·m^-2·s^-1·Pa^-1 for wet CO₂/CH₄ mixture can be observed at 353 K with a pressure drop of 0.4 MPa. Furthermore, the modified membrane exhibited stable separation performance during the 120-hour test for wet CO₂/CH₄ mixture at 353 K. The hydrophobic modification paves a way for SAPO-34 membranes in real applications.     

Plant-inspired biomimetic hybrid PVDF membrane co-deposited by tea polyphenols and 3-amino-propyl-triethoxysilane for high-efficiency oil-in-water emulsion separation

Membrane pollution caused by separating oily wastewater is a big challenge for membrane separation technology. Recently, plant-/mussel-inspired interface chemistry has received more and more attention. Herein, a high antifouling poly (vinylidene fluoride) (PVDF) membrane, coated with tea polyphenols (TP, extracted from green tea) and 3-amino-propyl-triethoxysilane (APTES), was developed to purify oil-in-water emulsions. ATR-FTIR, XPS and SEM were used to demonstrate the evolution of surface biomimetic hybrid coatings. The performances of the developed membranes were investigated by pure water permeability and oil rejection for various surfactant-stabilized oil-in-water emulsions. The experimental results revealed that the membrane deposited with a mass ratio of 0.1/0.2 exhibited ultrahigh pure water permeability (14570 L·m^-2·h^-1·bar^-1, 1 bar=0.1 MPa) and isooctane-in-water emulsion permeability (5391 L·m^-2·h^-1·bar^-1) with high separation efficiency (>98.9%). Even treated in harsh environment (acidic, alkaline and saline) for seven days, the membrane still maintained considerable underwater oleophobic property (148°–153°). The fabricated plant-inspired biomimetic hybrid membranes with excellent performances light a broad application prospect in the field of oily wastewater treatment.     

Overwhelming low ammonia escape and low temperature denitration efficiency via MnOx-decorated two-dimensional MgAl layered double oxides

Low temperature catalysts are attracting increasing attention in the selective catalytic reduction (SCR) of NO with NH₃. MnO_x-decorated MgAl layered double oxide (Mn/MgAl-LDO) was synthesized via a facile fast pour assisted co-precipitation (FP-CP) process. Compared to the Mn/MgAl-LDO obtained via slow drop assisted coprecipitation (SD-CP) method, the Mn/MgAl-LDO (FP-CP) has excellent activity. The Mn/MgAl-LDO (FP-CP) catalyst was shown to possess a high NO conversion rate of 76%-100% from 25 to 150 ℃, which is much better than the control Mn/MgAl-LDO (SD-CP) (29.4%-75.8%). In addition, the Mn/MgAl-LDO (FP-CP) offered an enhanced NO conversion rate of 97% and a N₂ selectivity of 97.3% at 100 ℃; the NO conversion rate was 100% and the N₂ selectivity was 90% at 150 ℃ with a GHSV of 60,000 h^-1. The Mn/MgAl-LDO (FP-CP) catalyst exhibited a smaller fragment nano-sheet structure (sheet thickness of 7.23 nm). An apparent lattice disorder was observed in the HRTEM image confirming the presence of many defects. The H₂-TPR curves show that the Mn/MgAl-LDO (FPCP) catalyst has abundant reducing substances. Furthermore, the enhanced surface acidity makes the NH₃ concentration of the Mn/MgAl-LDO (FP-CP) catalyst lower than 100 ml·m^-3 after the reaction from 25 to 400 ℃. This can effectively reduce the ammonia escape rate in the SCR reaction. Thus, the Mn/MgAl-LDO (FP-CP) catalyst has potential applications in stationary industrial installations for environmentally friendly ultra-low temperature SCR.     

Influence of surface etching pretreatment on PEO process of eutectic Al-Si alloy☆

To solve the problems generally encountered during the plasma electrolytic oxidation (PEO) of Al alloys with high Si content, a pretreatment of chemical etching was applied before the process. The influence of such pre-treatment was studied by SEM, EDS and XRD. The pretreatment presents a significant effect on positive voltage at the beginning stage of PEO, leading to higher voltage over the whole process. The difference between the pos-itive voltages of non-etched and etched specimens decreases gradual y with the increase of processing time. The pretreatment exhibits much less influence on the negative voltage. For the sample with surface pretreatment, the average growth rate of PEO coating is increased from 0.50 to 0.84μm·min?1 and the energy consumption is de-creased from 6.30 to 4.36 kW·h·μm?1·m?2. At the same time, both mullite and amorphous SiO2 contents are decreased in the coating.     

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation (NIPS) process was used to fabricate a series of sulfonated polyethersulfone (SPES) membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration (UF) process. SBA-15 was modified with 3-methacrylate-propyltrimethoxysilane (MPS) to form SBA-15-g-MPS. It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt. The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane. The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability, hydrophilicity, and antifouling properties. The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane. For the membrane containing 5% (mass) of SBA-15-g-PSPA (MSSPA5), the pure water flux was increased dramatically to 402.15 L·m^-2·h^-1, which is ~1.5 times that of MSSPA0 (268.0 L·m^-2·h^-1). The high flux rate was achieved with 3% (mass) of SBA-15 nanoparticles with retained high rejection ratio 98% for natural organic matter. The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.     

沼液余热回收对高温发酵沼气工程净产气率的影响

以瑞典Alviksgården养猪场高温发酵沼气工程为分析对象,通过传热模型计算发酵罐加热负荷,通过与江苏金坛永康农牧养猪场同等规模的中温发酵沼气工程对比,讨论高温发酵的容积产气率和余热回收对沼气工程净产气率的影响。结果表明虽然瑞典Alviksgården养猪场高温发酵沼气工程的加热能耗是江苏金坛永康农牧养猪场中温发酵沼气工程的2.1倍,但由于产气速率达到2.3 m³·m^-3·d^-1,增产的沼气量远远大于增温的能耗;若进一步在瑞典Alviksgården养猪场沼气工程中增加余热回收,可将沼气净产气率从82%提高至90%。相对于提高容积产气率,采用余热回收技术对降低高温发酵沼气工程的增温能耗、提高净产气率效果更加显著。     

A solar reactor for bio-diesel production from Pongamia oil: Studies on transesterfication process parameters and energy efficiency

Over exploitation of non-renewable energy reserves will lead to increase in price of petroleum fuels. Therefore there is a need for suitable and sustainable substitutes (renewable resource) for conventional fuels. In this study, an efficient and environmental friendly method for production of bio-diesel from Pongamia (Karanja) oil has been developed using a solar reactor. During the experimental study, the maximum temperature attained by the pongamia oil during the transesterification process was 64.1 ℃. The transesterification reaction was studied by varying different parameters such as reactant flow rate (5–20 L·h^-1), stirring speed (150–450 r·min^-1), catalyst mass loading (0.5%–2%) and methanol to oil ratio (3:1 to 15:1). The maximum biodiesel yield was 83.11% at a flow rate of 5 L·h^-1, stirring speed of 350 r·min^-1, a methanol to oil ratio of 15:1, catalyst mass loading of 1% and reaction time of 270 min. The physical and chemical properties of biodiesel was analyzed as per American Society for Testing Materials (ASTM) standards and it had density of 938 kg·m^-3, viscosity (28.7×10^-6 m²·s^-1), acid value (9.45 mg KOH·(g oil)^-1) and flash point (215 ℃). The energy efficiency of solar heating process was determined by comparing the net energy ratio of direct heating process and solar heating process. For solar heating the net energy ratio (NER) was found to be 31.85 against 5.73 for direct heating. Similarly, net energy efficiency index was calculated for 10 kg production scale and was found to be increasing when scaled up which means that the solar heating process is more effective even in scaled up production.     

Chemical looping gasification of sewage sludge using copper slag modified by NiO as an oxygen carrier

Chemical looping gasification (CLG) provides a novel approach to dispose the sewage sludge. In order to improve the reactivity of the calcined copper slag, NiO modification is considered as one of the good solutions. The copper slag calcined at 1100 ℃ doped with 20 wt% NiO (Ni20-CS) was used as an oxygen carrier (OC) in sludge CLG in the work. The modification of NiO can evidently enhance the reactivity of copper slag to promote the sludge conversion, especially for sludge char conversion. The carbon conversion and valid gas yield (V_g) increase from 67.02% and 0.23 m³·kg^-1 using the original OC to 78.34% and 0.29 m³·kg^-1 using the Ni20-CS OC, respectively. The increase of equivalent coefficient (Ω) facilitates the sludge conversion and a suitable Ω value is determined at 0.47 to obtain the highest valid gas yield (0.29 m³·kg^-1). A suitable steam content is assigned at 27.22% to obtain the maximum carbon conversion of 87.09%, where an acceptable LHV of 12.63 MJ·m^-3 and V_g of 0.39 m³·kg^-1 are obtained. Although the reactivity of Ni20-CS OC gradually decreases with the increase in cycle numbers because of the generation of NiFe₂O_4-δ species, the deposition of sludge ash containing many metallic elements is beneficial to the sludge conversion. As a result, the carbon conversion shows a slight uptrend with the increase of cycle numbers in sludge CLG. It indicates that the Ni20-CS sample is a good OC for sludge CLG.     

Preparation of Ni/bentonite catalyst and its applications in the catalytic hydrogenation of nitrobenzene to aniline

Ni supported on bentonite was prepared by the impregnation method with different nickel contents, applied to the hydrogenation of nitrobenzene to aniline in a fixed-bed reactor, and it was characterized by X-ray diffraction(XRD), H_2-temperature programmed reduction(H_2-TPR), and X-ray photoelectron spectrometry(XPS). The results showed that Ni/bentonite catalyst with 20 wt% nickel content provided a higher conversion of nitrobenzene and selectivity of aniline compared to other catalysts. Ni O was the precursor of the active component of the catalyst, and the small crystallite size as well as the highly dispersed Ni O on the Ni/bentonite-20 catalyst, contributed to the catalytic performance. The hydrogenation of nitrobenzene was carried out at 300 °C with a H_2 gaseous hourly space velocity of 4800 ml·(g cat)~(-1)·h~(-1)and a nitrobenzene liquid hourly space velocity of4.8 ml·(g cat)~(-1)·h~(-1)over Ni/bentonite-20. A 95.7% nitrobenzene conversion and 98.8% aniline selectivity were obtained. While the nitrobenzene liquid hourly space velocity was 4.8 ml·(g cat)~(-1)·h~(-1), the yield of aniline was more than 95.0% during a 10-hour reaction.     

Electrospinning organic solvent resistant preoxidized poly(acrylonitrile) nanofiber membrane and its properties

A high performance preoxidized poly(acrylonitrile) (O-PAN) nanofiber membrane with excellent solvent resistance, thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane. The performance of resultant O-PAN nanofiber membrane was optimized by altering the PAN concentration and preoxidation temperature. The results showed that the O-PAN nanofiber membrane which made from PAN concentration of 14% (mass) and preoxidation temperature of 250.0 ℃ have a more optimal comprehensive performance. In the long-term separation test of SiO₂ particle (1 μm) in DMAc suspension, the permeate flux of O-PAN nanofiber membrane stabilized at 227.91 L·m^-2·h^-1 (25 ℃, 0.05 MPa) while the SiO₂ rejection above 99.6%, which showed excellent solvent resistance and separation performance. In order to further explore the application of the O-PAN nanofiber membrane, the O-PAN nanofiber membrane was treated with fluoride and used in oil/water separation process. The O-PAN nanofiber membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance with the permeate flux about 969.59 L·m^-2·h^-1 while the separation efficiency above 96.1%. The O-PAN nanofiber membrane exhibited a potential application prospect in harsh environment separation.     

Activation mechanisms on potassium hydroxide enhanced microstructures development of coke powder

Coke powder is expected to be an excellent raw material to produce activated carbon because of its high carbon content. Potassium hydroxide (KOH), as an effective activation agent, was reported to be effective in activating coke powder. However, the microstructures development in the coke powder and its mechanisms when KOH was applied were still unclear. In this study, effects of KOH on the microstructure activation of coke powder were investigated using the surface area and pore structure analyzer, scanning electron microscope (SEM) and thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS), etc. Results revealed that the addition KOH at its lower ratio (mass ratios of KOH and coke powder in a range of 0.5 and 1) decreased the specific surface area and average lateral sizes, but sharply increased of the specific surface area to 132 m²·g^-1 and 355 m²·g^-1 and decreased of the space size of aromatic crystallites upon the further increase of the KOH addition amounts (ratios of KOH and coke powder in a range of 3 and 7), generating a number of new micropores and mesopores. The mechanisms study implied surface reactions between KOH and aliphatic hydrocarbon side chain and other carbon functional groups of the coke powder to destruct aromatic crystallites in one dimension and broaden pores at lower KOH addition. In the activation process, KOH was decomposed to be more active components, which can be rapidly destruct the aromatic layers in spatial scope to form developed porous carbon structures within coke powder at higher KOH addition.     

木质框架土壤渗滤系统处理养猪废水厌氧消化液的效能

为处理高氨氮、低C/N比的养猪废水厌氧消化液, 构建了具有缓释碳源特性的木质框架土壤渗滤系统(WFSI), 并通过运行测试了进水浓度和表面水力负荷(SHL)对系统处理效能的影响。在SHL为0.2 m³·m^-2·d^-1条件下, 当进水COD和NH₄⁺-N平均浓度分别从152和175.5 mg·L^-1提高到421和788.7 mg·L^-1时, 系统对COD的去除率从52.3%提高到61.2%, NH₄⁺-N去除率从84.2%下降到61.5%, TN去除率从28.6%提高到了33.5%, NH₄⁺-N和TN去除负荷分别达到了75.5和41.7 g·m^-3·d^-1。当SHL提高为0.32 m³·m^-2·d^-1时, 系统仍能维持运行, 但处理效能受到显著影响。在进水COD 和NH₄⁺-N分别为265和465 mg·L^-1左右时, COD、NH₄⁺-N及TN的去除率分别平均为56.5%、53.3%和20.9%。木质填料及其附着层形成的NH₄⁺-N浓度梯度, 可使系统承受较高的SHL的同时获得缓释碳源, 并保护氨氧化细菌免受自由氨毒性。     

废CeO x -MnO x 基SCR脱硝催化剂还原酸浸综合回收铈锰

废选择性催化还原（SCR）脱硝催化剂中含有大量的有价金属,直接废弃易造成资源浪费及环境污染。以废CeO _x -MnO _x 基SCR脱硝催化剂为原料,采用热力学分析结合湿法冶金实验方法,研究了浸出条件对Ce、Mn元素浸出率的影响。结果表明,废催化剂直接酸浸Ce、Mn元素浸出率低,还原-酸浸Ce、Mn元素热力学条件上可行,抗坏血酸对Ce、Mn高价氧化物有明显的还原作用。当抗坏血酸质量分数为30%、硫酸浓度2mol/L、液固比6∶1、搅拌速度350r/min、80℃恒温反应5h时,Ce、Mn的浸出率分别达到92.09%、95.51%。加入抗坏血酸后,部分Ce⁴⁺和Mn⁴⁺还原为Ce³⁺和Mn²⁺,Ce⁴⁺/Ce的比值由75.82%降低到71.62%,Mn⁴⁺/Mn的比值由29.39%降低到27.17%,同时削弱了高价Ce辅助低价Mn向高价Mn转化的作用,使得Ce、Mn高效浸出,为CeO _x -MnO _x 基废催化剂中Ce、Mn资源化利用奠定了基础。